Route reliability record
HLN→DEN
Helena to Denver
- Flights
- 844
- Period
- July 2025 to June 2026
- Distance
- 594 mi
- Carriers
- 1
This route lands a B+, about a point better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That is a workable record, not a spotless one. That rests on 844 HLN to DEN flights, with a median arrival 11 minutes early.
Best time to fly HLN to DEN: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 89.8% of the time and Tuesday flights 85.6%, against 78.9% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.9%
Arrivals under 15 minutes late, of 830 completed flights
Avg delay
105 min
Across delayed arrivals only, not all flights
Cancelled
0.71%
National rate is 1.81%
Best carrier
SkyWest
78.9% on time across 844 flights
These figures cover 844 flights between July 2025 and June 2026. Beyond the headline rate, 10.7% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Which airline is most reliable on HLN to DEN
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 844 | 78.9% | 105 min | 0.71% | B+ |
Flight by flight
Flights on HLN to DEN
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 34 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am365 flights89.8%
- 8am–11am—
- 11am–2pm—
- 2pm–5pm364 flights75.3%
- 5pm–8pm115 flights55.4%
- 8pm–5am—
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 55.4% on time, against 89.8% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5am–8am window is the busiest, with 365 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 42 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 51.2% on time, 42 points below May, the best at 93.5%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. August was the busiest month here, with 93 flights.
Across the week, Tuesday is the strongest day at 85.6% on time and Friday the weakest at 74.6%. 11 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 18,000 reported delay minutes.
- 37%Carrier
- 27%National Airspace System
- 22%Late-arriving aircraft
- 13%Extreme weather
Extreme weather accounts for 13% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.2 times the usual weather exposure. The split is drawn from 18,409 reported delay minutes.
The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 6,837 of the 18,000 delay minutes reported here.
Cancellations are rare at 0.71%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.7% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 594 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg runs 78.9% on time across 844 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 844 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
Work out the risk of missing a connection in DEN after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 844 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 78.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 830 completed flights over 12 months sit behind that.
Common questions
HLN to DEN questions
How often is HLN to DEN delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.1% of the 844 flights in this analysis, against 22.4% nationally. Delayed flights are late by close to two hours on average.
How reliable is HLN to DEN compared with the rest of the country?
78.9% of flights arrive on time here against a national 77.6%, a difference of about a point in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on HLN to DEN?
The 5am–8am departure window is the strongest at 89.8% on time. The 5pm–8pm window is the weakest at 55.4%, 34 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on HLN to DEN?
July is the weakest month at 51.2% on time, compared with 93.5% in May. Across the year that is 42 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- DEN to HLN — the return legseparate record
- Denver International (DEN) delay statistics
- HLN to SLC, a related route95.9%
- PHX to DEN, a related route77.2%
- SLC to DEN, a related route77.8%
- SkyWest Airlines on-time record78.9%
- The best time of day to fly, according to 7.04 million flight records
- How often a connection fails at the major US hubs
Direction matters. HLN to DEN and DEN to HLN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.